I don't think anyone is saying that not smoking isn't the best option. They just aren't agreeing that some exposure to the low amounts of residual chemicals is necessarily harmful (or more harmful) to long term health than what is already in our daily environment and food chain. Nor is anyone saying that the smell doesn't linger on clothing, skin, hair and any other porous material or furnishing, just that while the smell is unpleasant, so is the smell of a lot of things in our environment that aren't banned. But people react differently if it is cigarette smoke.
I haven't smoked in many years, and I hate the smell, but at the same time, I don't think getting an occasional whiff of smoke in passing someone on the sidewalk, or being exposed to the residual (and very unpleasent) odors and chemicals is doing significant damage to my health. The exceptions, of course, would be those folks that truly have allergies to smoke or specific health problems where the smell of smoke triggers a reaction. I kind of compare it to the lingering scent of a skunk. It smells bad, and contains residual chemicals...but the amount of exposure is low enough that unless you are directly sprayed, there are not necessarily negative affects to your health